High-frequency generator

Abstract

The power stage at the output of a high-frequency generates operates in class D and comprises a voltage supply and a common earth, a first and a second switch linked to the common earth and periodically switched on at a high frequency F; these switches are linked to two common-mode inductors connected in a Guanella balun. Each common-mode inductor comprises two inductive lines with strong mutual coupling. The first switch is linked to the input of the first inductive line but not to the second, third and fourth lines and the second switch is linked to the input of the fourth inductive line but not to the first, second and third lines, the output of the first inductive line is linked to an output of the generator, the output of the fourth inductive line is linked to an internal resistor, the inputs of the second and third inductive lines are linked to the supply voltage source, the output of the third inductive line is linked to the output of the first inductive line and the output of the second inductive line is linked to the output of the fourth inductive line.

The invention claimed is: 
     
       1. A high-frequency generator comprising a class D power stage comprising a voltage supply and a common earth, a first pair of switches and a second switch linked to the common earth and respectively controlled by two control signals to be switched on periodically and non-simultaneously at a frequency F, and a first pair of second common-mode inductors comprising a first and second common-mode inductors coupled in a Guanella balun, comprising for the first common-mode inductor a first and a second inductive line with strong mutual coupling, each having an input and an output, and for the second common-mode inductor a third and a fourth inductive line, each having an input and an output, wherein the first switch is linked to the input of the first inductive line but not to the second, third and fourth inductive lines and the second switch is linked to the input of the fourth inductive line but not to the first, second and third lines, the output of the first inductive line is linked to an output of the power stage of the generator, the output of the fourth inductive line is linked to an internal impedance, the inputs of the second and third inductive lines are linked to the voltage supply, the output of the third inductive line is linked to the output of the first inductive line and the output of the second inductive line is linked to the internal impedance or to another internal impedance. 
     
     
       2. The generator of  claim 1 , wherein the output of the second inductive line is linked to the output of the fourth inductive line. 
     
     
       3. The high-frequency generator of  claim 1 , wherein the switches are transistors of the same type. 
     
     
       4. The high-frequency generator of  claim 1 , wherein the common-mode inductors are each formed by two juxtaposed conductors coiled in the same direction on a magnetic core. 
     
     
       5. The high-frequency generator of  claim 1 , further comprising a capacitor placed in series between the connection point of the outputs of the first and the third inductive lines and the output of the generator. 
     
     
       6. The high-frequency generator of  claim 5 , further comprising another capacitor is placed in series between the output of the fourth inductive line and the internal impedance. 
     
     
       7. The high-frequency generator of  claim 1 , further comprising a band-pass filter placed between a connection point of the outputs of the first and the third inductive lines and the output of the generator. 
     
     
       8. The high-frequency generator of  claim 1 , further comprising another pair of switches and another pair of common-mode inductors formed and associated together in the same way as the first pair of switches and the first pair of common-mode inductors, the output of the first line of the second pair of common-mode inductors being linked to the output of the first line of the first pair. 
     
     
       9. The high-frequency generator of  claim 8 , wherein the control signals of the second pair of switches are identical to the control signals of the first pair. 
     
     
       10. The high-frequency generator of  claim 8 , wherein a conduction duty cycle of the switches of the second pair is smaller than a conduction duty cycle of the first pair, conduction times of the switches of the second pair being located during conduction times of the corresponding switches of the first pair.